CNC Milling Service

Common Metal Machining Techniques

Common Metal Machining Techniques

Table of Content

Introduction

Metal machining has progressed from traditional manual metal cutting to micromachining with lasers. Machining is a broad term that refers to a wide range of processes and technologies used in production.

Learning the fundamentals of metal machining is essential for new business owners and aspiring metal part suppliers. Material is removed from a workpiece during the machining process. Metal is shaped into the desired design using power machine tools to make metal parts or components in a variety of applications. Machining can also be done on any existing part, such as a forging or an investment casting.

In this article, you’ll learn more about the metal machining process so you can use it to help you choose the best manufacturing procedures for your products and satisfy the needs and preferences of your customers.

What is Metal machining

Metal machining is an industrial technique for making metal components, tools, and machinery. It entails a number of steps to produce the proper form, hole diameter, size, texture, and finish of the final product.

Furthermore includes utilizing machine tools to shape a work-piece into a specific shape. During the manufacturing process, most  if not all  components and metallic items require some form of machining. Other materials, such as plastics, rubber, wood, and paper products, are frequently machined.

Machining technology types

Burning Machining Technology

What if we told you that there are several different forms of burning machining technology? Burning and welding machine tools are used to heat up the work-piece to shape it. They are known to burn through various materials.

· Laser cutting technology

Laser cutters melt, burn, or evaporate materials by emitting a high-energy, narrow light beam. This method is ideal for etching patterns or forming steel into a solid piece of art. Laser cutting offers advantages such as extreme composition and high-quality service finishes.

· Oxyfuel cutting technology

To cut and melt away materials, this kind of machining employs a combination of oxygen and fuel gas. Because propane, hydrogen, gasoline, or acetylene molecules are extremely flammable, they are typically used in this process.

· Plasma cutting technology

This tool works by firing a flow of plasma into an electrical arc. As a result, inert gases are transformed into plasma. Of course, while dealing with plasma, it might become extremely hot to the touch.

Erosion Machining Technology

Although burning tools utilise heat to remove extra material, erosion machines use electricity or water to remove material from your workpiece.

· Water jet cutting technology

Water jet cutters, use a highly pressurised water stream to slash through a variety of materials. To degrade materials quicker than ever before, simply mix some form of abrasive grit into the stream of water. Water jet cutters are typically used on materials that have been distorted or damaged as a result of heat exposure.

· Electric discharge machining technology

To make tiny craters, electric discharge machining tools are utilised to discharge electrical arches. This improves the pace of “full cuts.” Electric discharge machining is also employed in applications that need complex forms.

Electric discharge machining tools can also be used to cut through difficult materials. Electric discharge machining tools limit the number of ferrous alloys by using a base material to conduct electricity.

Metal machining techniques

  • Turning
  • Milling
  • Grinding
  • Boring
  • Drilling
  • Sawing
  • Broaching
  • ECM/EDM

Turning

Turning is the simplest machine operation, including clamping a workpiece firmly onto a spinning plate or mandrel. The cutting tool is kept against the workpiece in a fixture mounted on a moving slide while it revolves. The slide can be moved up and down the length of the workpiece as well as closer to and farther away from the centre line. These straightforward machining methods are perfect for efficiently removing huge amounts of material. A drill bit installed on the tailstock can also bore precise holes down the workpiece’s centerline.

On the outer circle of a round object, lathes are employed to create concentric forms. Many round or circular features are manufactured on a lathe, including slots, ring grooves, stepped shoulders, internal and external threads, cylinders, and shafts. They can also generate surface finishes that are notably smooth and homogeneous.

Milling

Milling differs from turning in that the workpiece remains stationary while the cutting tool spins on a spindle. In most cases, the workpiece is held horizontally in a machine vise that moves in the X and Y directions. The spindle travels in the X, Y, and Z axes and carries a variety of cutting tools.

A mill can drill holes and bores, but it is best at removing stock from more complex and asymmetrical pieces. Mills are used to make square/flat faces, notches, chamfers, channels, profiles, keyways, and other features that are angle-dependent. The majority of CNC machine tool operations are performed by milling and turning together. Cutting fluid is used to cool the workpiece and cutting tool, lubricate it, and flush metal particles away in all metal machining operations.

Grinding

Grinding is a machining process that involves removing a small amount of material from a workpiece with an abrasive turning wheel to achieve a fine finish. Grinding can also be used to texturize the object or make light cuts.

· Surface grinding

For many applications, a highly smooth surface on metal items is critical, and the best method to achieve this is with a grinder. The grinder consists of a spinning disc covered in a coarse abrasive grit. The workpiece is mounted on a table and is either moved back and forth laterally beneath the abrasive wheel or held still while the wheel rotates. Naturally, this procedure can only be used on faces that are not obstructed by protrusions protruding from the surface.

Depending on the material being ground, different types of abrasives are utilized. Because the heat and mechanical stress of the grinding process might harm the work piece, it’s important to keep tool speed and temperature under control.

· Cylindrical grinding

Surface grinding and lathe turning are used in this process. A circular or cylindrical grinding wheel is normally spun against the workpiece’s surface while it is maintained stationary. On both interior and outside diameters, cylindrical grinders can be utilized all the way through the length of the part or at partial depths.

This procedure has the advantage of producing exceedingly precise and exact tolerances with a very smooth surface texture.

· Optical grinding

Surface grinding and lathe turning are used in this process. A circular or cylindrical grinding wheel is normally spun against the workpiece’s surface while it is maintained stationary. On both interior and outside diameters, cylindrical grinders can be utilized all the way through the length of the part or at partial depths.

This procedure has the advantage of producing exceedingly precise and exact tolerances with a very smooth surface texture.

Boring

Boring is the process of expanding already drilled or cast holes. Line boring (one of both ends supported by a boring bar), back boring (boring a hole in the back half of the workpiece), and lathe boring are all examples of boring (enlarging a hole with a single-point cutting tool to create tapered or square holes)

Boring can also be termed as method of enlarging previously cut holes in a workpiece. Drilling can be used to make the first holes. Boring, unlike drilling, employs a single-point cutting instrument.

Drilling

Drilling is a machining method that employs drill bits to create cylindrical holes in solid materials; it is one of the most important machining techniques since the holes created are often utilized to aid with assembly. Drill presses are most commonly used, but lathes can also be used. Drilling is a pre-processing phase in most manufacturing operations that results in finished holes that are then tapped, reamed, bored, or otherwise modified to produce threaded holes or bring hole dimensions within acceptable tolerances. Drill bits will generally cut holes larger than their nominal size and holes that are not necessarily straight or round due to the bit’s flexibility and desire to seek the path of least resistance. As a result, drilling is typically specified undersize, with machining to get the hole to its final size.

The drill bits used had two helical grooves running up the shaft. The “fluting” carries the pieces, or swarf, out of the hole when the bit enters the material. Each type of material has a recommended drill speed and feed.

Sawing

Metals are typically sawed using cut-off machines to make shorter lengths from bars, extruded shapes, and other materials. Band saws, both vertical and horizontal, chisel away at the material with continuous loops of toothed bands. The band’s speed varies depending on the material, with some high-temperature alloys requiring a sluggish 30 fpm and softer materials like aluminium requiring 1000 fpm or more. Power hack saws, abrasive wheel saws, and circular saws are examples of other cut-off machines.

Laser engraving

Laser engraving is best for high-precision labeling or marking, as it uses laser technology for permanent marking, flexibility, rapid cycle times, and production line integration. It’s a low-cost method of marking metal items.

Laser technology allows for precision metal stamping via laser engraving. Labeling metal products with appropriate serial numbers, identity codes, brand names, and model numbers can be done with precision and uniformity using metal precision stamping. Using laser technology will impress your clients and investors.

Broaching

Broaching is used to make square holes, keyways, and spline holes, among other things. The broach is made up of several teeth that are placed in a file-like pattern, with each tooth slightly larger than the one before it. The broach makes a series of deeper cuts as it is pulled or pushed through a prepared leader hole (or beyond a surface). Vertical press machines are frequently used for push broaching. Pull broaching is commonly done with vertical or horizontal devices that are generally hydraulically propelled. Cutting speeds for high-strength metals range from 5 to 50 fpm for softer metals.

ECM/EDM

· ECM

Electro-Chemical Machining is a type of reverse electroplating that results in burr-free holes with excellent surface finishes. The workpiece is not subjected to any thermal pressures because it is a cold machining technique.

· EDM

These are non-mechanical materials removal methods that rely on corrosive sparks or chemicals. Electric discharge machining involves sending a spark from an electrode to the surface of a conductive workpiece through a dielectric fluid. Small diameter holes, die cavities, and other fine features can be manufactured with this technology. The thermal characteristics and conductivity of the metal, rather than hardness, influence the discharge rate.

When choosing CNC machine cutting tools, there are the factors to consider

Material and Features of the Workpiece

The material of the workpiece has a big impact on tool selection. Aluminum, ductile iron, and grey iron castings are the most often machined materials at Stecker Machine. For each material, we have favourite CNC machining metal cutting tools. Engineers like to start with tried-and-true standardised tools, which reduces risk, inventory, and expenses.

Drills, mills, and taps are used to machine various features, and standard tooling is available for each tool type and material. Stecker, for example, offers three basic 90° square shoulder face mills: one for cutting aluminium, one for machining ductile iron, and one for machining grey iron. Aluminum has the highest machinability of these materials, hence aluminium tooling has greater surface feet per minute (SFM) standards, allowing it to run faster.

Volume of Production

In general, high-volume projects require specialised, high-end cutting tools, while low-volume ones use more economy-level tooling. It all boils down to economies of scale, with the enormous volume of components to be produced justifying the expensive cost of high-end, feature-specific tooling.

Possibilities for Combinations

In CNC machining, multiple-feature tools can save a lot of money and time. When several operations — three, four, or more — may be done by a single tool, cycle duration increases while tool changeover time decreases.

For example, a well designed insertable combo tool can drill and chamfer in three distinct ways, completing the work in one pass with one tool rather than six (and six passes). Yes, that custom-made, multi-feature tool could set you back $3,000, but the savings quickly pile up to cover the price, especially on a high-volume project.

Capacity of Machines

Most cutting tools are compatible with CNC machines. However, this does not always imply that those machines are the most efficient. Engineers and operators understand that a higher horsepower machine (with a larger taper) allows them to use multi-functional combo tools.

Smaller castings do not require the use of hoists to move them, whereas larger castings must. Indeed, developing a fixture that can run two or three tiny components at once on a bigger machine may provide potential for enhanced efficiency. This is an illustration of how huge machine does not always imply massive casting.

Material of the tool

The same cutting tool can be produced out of a variety of materials, some of which are more durable (and therefore more expensive) than others.

Solid carbide is a cutting tool material that is extremely durable. A PCD-tipped tool, on the other hand, achieves another level of durability. The hardest current cutting tool is PCD, or polycrystalline diamond, which is created by sintering diamond particles with a metallic binder.

A PCD-tipped drilling tool has a tool life of around 4X that of a solid carbide tool (2,500 pieces versus 10,000), but it can also operate 25% faster. The cost difference between the two (about $180 for carbide against $960 for PCD) is countered by the difference in production (higher spindle speed, extra feed rate, AND labour, setup, and other savings).

Strategy

Engineers commonly design a best-case scenario (best tooling, aggressive cycle times, high-end fixturing) and a “Plan B” scenario when determining how a new project will be completed in the shop (less expensive tooling, less powerful machines, etc.). The temptation is to keep costs down by choosing a less expensive solution, but this usually implies that tooling suffers.

The flaw in that argument is that it fails to account for potential tooling issues, which not only cost as much as the initial best-case scenario, but also add the cost of wasted time to the project.

Experience is invaluable

Some CNC machine businesses have more knowledgeable employees than others. Nothing can match the knowledge gathered from decades of successful CNC machine projects. These frontrunners are experienced in managing projects from conception to completion, and they have the necessary processes in place as well as many of the necessary tools.

So, how does a newcomer get into a seasoned CNC machine shop? After all, even the top higher education CNC programmes and training sessions do not teach tool selection. It’s an example of tribal knowledge in this case: skill passed down from engineer to engineer, typically in high-end CNC machine shops.

Summary

You now have a better understanding of the various types of machining and processes involved. Machining involves the use of various equipment and processes, depending on the workpiece or material utilised, as well as the desired product outcome. Mechanical, abrasive, thermal, or chemical ways of removing material may be used in the machining process to achieve the best product design and features.

Understanding metal machining will help you plan whether you’re a first-time entrepreneur or someone who wants to manufacture and provide metal parts for the automotive, electronics, and other industries. While there is a lot to learn, speaking with a metal machining professional can help you achieve your objectives.

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